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The results of some tests recently completed are presented. No attempt is made to develop the theory involved. It is intended to describe only the actual tests, the conditions under which they were carried out and the results obtained. Superficially, it would seem obvious that the torsional strength of a multiple-splined shaft is greater than that of a full round shaft having a diameter equal to the small diameter of the splined shaft. Data on this and related questions were sought experimentally. A series of tests was run on 15 carefully machined shafts. The dimensions shown are the actual ones of the test-pieces, there not being more than 0.0005-in. variation in any shaft from the diameters shown. Heat-treating was very carefully carried out, and each specimen carefully checked by Brinell instrument on the ends and by scleroscope throughout the length. The Brinell numbers were all between 220 and 235, and the extremes of scleroscope hardness were 38 and 43.

The author states preliminarily that it is believed that never before in the history of the Society of Automotive Engineers has a single problem been so universally studied as the fuel problem that is confronting the industry today. It is also believed that never before has the industry had a problem which includes such a wide scope of work. The solution calls for the service of every class of engineer, inventor and scientist. The paper does not attempt to give highly scientific information; its real purpose is to appeal for a broader viewpoint and to give illustrations and tests which show that the solution of a problem may lie in an entirely different method than that which often becomes stereotyped by sheer usage, rather than by its specific merit. In the solution of the fuel problem we undoubtedly will have to change some of our old habits, replacing them by studiously worked out viewpoints.

In this day of transportation engineering, the requirements of each customer must be diagnosed accurately and the economic waste due to wrong selling eliminated. Stating that 32 classes of trades, divided into 350 sub-classes, use motor trucks, the author expresses the view that, in applying the science of selling by analysis, it is necessary to know the cost of shipping every pound of goods, deducing in turn the correct size of truck for a given kind of work. Referring to the fact that a truck cannot be designed to stand up under all conditions and that selling a truck which is unsuitable for a particular task means a dissatisfied customer, the author gives the opinion that a truck of mediocre merit will in many cases perform more satisfactorily than the best truck built operating under improper conditions.

The nature of flame propagation in an automobile engine cylinder has, for some time, been the subject of much discussion and speculation. However, very little experimental work has been done on flame movement in closed cylinders with a view to applying the knowledge directly to the internal-combustion engine. It has become recognized that knocking is one great difficulty which attends the use of the higher-boiling paraffin hydrocarbons, such as kerosene, and that knocking is one of the major difficulties to be overcome in designing higher-compression and hence more efficient engines. It was desirable, therefore, to determine, if possible, the nature and cause of the so-called fuel knock in an internal-combustion engine. The work described in this paper was undertaken to determine the characteristic flame movement of these various fuels and the physical and chemical properties which influence this flame propagation.

Stating that asphalt, brick and concrete-slab road-surfaces are the only pavements that have given satisfaction for automobile traffic, the author believes further that thus far the concrete-slab surface is the only one worthy of consideration for such traffic. He discusses the merits and demerits of these surfaces and includes an enumeration of the factors that combine to produce a thoroughly satisfactory road surface. Passing to a detailed review of the bearing value of soils and the correction of road failures, the author presents data and illustrations in substantiation of his statements and follows this with a consideration of the reinforcing of a concrete road-slab with steel.

The paper describes the results obtained from making visual observations of the paths followed by the several portions of the air-stream. One of the passages being considered was half-sectioned in a plane about which the passage was symmetrical; that is, a plane containing the axes of the several parts of the passage. A flat glass plate was then cemented on to complete the half-passage. With the outlet end of such a passage connected to an engine intake, any sort of flow encountered in engine practice can be reproduced. By introducing gasoline with the entering air, a tracery of fine sharply defined lines on the glass is produced and this was photographed, as is described in detail. Varied shapes of passages were studied in this manner. These are illustrated and the variations in the results under differing conditions are discussed.

It is of course impossible to consider propeller design very much in detail in a paper of this nature. It can be said, however, that the airfoil theory, in connection with the inflow theory, has given very good results and proved exceedingly valuable for the aerodynamic design of propellers. Both theories, however, in the present state of knowledge, must be applied with a number of empirical factors. Propeller-design theories and the subject of aerodynamics are discussed mathematically, as well as the elements governing the best propeller diameter for obtaining the highest thrust. Consideration is given in detail to steel, adjustable-pitch and reversible propellers as well as to those made of laminated construction consisting of sheets of paper fabric impregnated with bakelite as a binder. The mathematical considerations that apply to propellers when reversed in flight, the time and distance required to stop when landing and the propeller stresses are enumerated and commented upon.

After stating that the meaning of the term “gasoline” seems to be generally misunderstood for the reason that it has been assumed that gasoline is, or ought to be, the name of a specific product, the author states that it is not and never has been a specific product and that although gasoline has a definite and generic meaning in the oil trade it has no specific meaning whatever. It means merely a light distillate from crude petroleum. Its degree of lightness, from what petroleum it is distilled and how it is distilled or refined are unspecified. Specifically, “gasoline” is the particular grade of gasoline which at a given moment is distributed in bulk at retail. It can be defined with reasonable precision as being the cheapest petroleum product acceptable for universal use as a fuel in the prevailing type of internal-combustion engine.

Automobile body building derives its origin from carriage body building, which was highly developed before automobiles were thought of. The introduction of automobile bodies fitted to a metal frame changed body builders' rules and calculations. The influence of the metal frame is discussed briefly and the limiting sizes of body members are considered also. According to the ideas expressed, the weight of bodies can be reduced if the metal frame is designed so as to support the weight of the passengers and the body. The dead-weight also can be reduced if the frame is built in proportion to the amount of weight carried, the number of passengers and the style of bodies being considered. But in the construction of enclosed bodies, as in sedans, coaches and broughams, very little weight can be saved if stability, durability and lasting quality are to be retained.

The field of body engineering is broader than it is ordinarily considered to be; the author's intention is to bring to the attention of the automotive industry the breadth and scope of body engineering and outline the way this side of the industry can be considered and developed. After describing the body engineer's position, the author then discusses at some length the conflict between art and economy in this connection. He classifies a body-engineering department under the six main divisions of body construction, open and closed; sheet metal, body metal, fenders, hood, radiators and the like; trimming; top building; general hardware; painting and enameling, and comments upon each. Following this he elaborates the reasons for need of attention to details in body designing and mentions the opportunity there is at present for bringing the materials used in body construction to definite standards.

The data given in this paper were obtained from an investigation by the Bureau of Mines in cooperation with the New York and New Jersey State Bridge and Tunnel Commissioners to determine the average amount and composition of the exhaust gases from motor vehicles under operating conditions similar to those that will prevail in the Hudson River Vehicular Tunnel. A comprehensive set of road tests upon 101 motor vehicles including representative types of passenger cars and trucks was conducted, covering both winter and summer operating conditions. The cars tested were taken at random from those offered by private individuals, corporations and automobile dealers, and the tests were made without any change in carbureter or other adjustments. The results can therefore be taken as representative of motor vehicles as they are actually being operated on the streets at the various speeds and on grades that will prevail in the tunnel.

The purpose of piston rings in an internal-combustion engine is to reduce to a minimum the leakage of gas from and the seepage of oil into the combustion-chamber. Asserting that the widely held idea that the leakage of gas past the piston can be eliminated by the use of good piston-rings is incorrect, the author states three possible paths for such gas-leakage and, after commenting upon them, discusses diagonal and lap joints and the subject of leakage with special reference to them. After considering the design of rings for gas-tightness, the author shows a fortunate mathematical relationship, in connection with the application of uniform radial pressures, regarding the bending-moment stresses. Oil leakage is treated in a similar manner and the conclusion is reached that the properties of the material used are of extreme importance.

Stating that the knowledge now available does not permit an exact scientific definition of flame and giving the reasons, in this paper the author regards flames as gases rendered temporarily visible by reason of chemical action, discusses their physical rather than their chemical aspects and, unless otherwise indicated, refers to the flames of common gasoline and kerosene only. To gain a reasonably clear understanding of the requirements and characteristics of the different kinds of flame, it is necessary to begin with a study of atoms and molecules. The author therefore discusses the present atomic theory, the shape of the atom and molecular structure, and follows this with a lengthy detailed description of the beginning of combustion. The requirements and characteristics of the inoffensive variety of combustion are considered next and nine specific remedies are given for use in accomplishing the burning of heavy fuels with a blue flame in present engines.

The majority of the reputable truck builders are attempting to build a high-quality product that will operate over a period of years with the minimum of maintenance expense; however, many designers lose sight of the effect of shocks and strains, which is of even greater importance. Stating that a truck is scrapped for some one or a combination of the three reasons of obsolescence of design, wear on vital parts that cannot be replaced economically and failure of parts due to shock loads, fatigue or crystallization, the author comments upon these and then discusses chassis strains under five specific headings, illustrations also being given.

The paper surveys the differences between American and European conditions in the automotive industry and then considers briefly the reasons for them. The governing conditions are stated and their effects are traced. The subjects discussed include motorcycles and small cars, road conditions, car idiosyncracies, selling conditions in Europe, and a comparison of design in general. The differences of practice are stated and commented upon. Six specific points are emphasized in the summary. The author states that the outlook for American cars the world over is seemingly good. In recent American designs, equal compression - volumes are often assured by machining the heads; six-cylinder crankshafts have seven bearings and are finished all over in the circular grinding machine; pressure lubrication is used for all moving parts of the engine; and in all ways the highest practice is aimed at. America is trying to improve the quality without increasing the cost.

The author describes a process for drying coats of paint and varnish more rapidly than is possible with natural means, by adding heat and moisture simultaneously to the air surrounding the siccative coatings, through the employment of mechanical devices. The use of a fan and conditioning equipment to produce air circulation allows the process to be adapted readily to modern factory-schedules. Atmospheric conditions suitable for drying are discussed at some length as being a composite of sensible temperatures and relative degrees of humidity, and several humidifying devices are described and illustrated. Color control of paint by this means of drying is mentioned, examples being given, and numerous photographs showing installations of artificial drying equipment in use at various automobile plants are presented.

The author considers first the materials available for construction, in connection with the S.A.E. standard specifications, and presents a comparison of the different metals with comments thereon. In regard to metallurgical problems the designer's first task is to determine what the various stresses in the parts are and their magnitude; hence, a true appreciation of the terms “shock” and “fatigue” is necessary; a somewhat lengthy explanation of their meaning is given. The construction features of the different parts of the tractor are treated in general, no attempt being made to cover details; comments are presented on front axles, wheels, bearings, cylinders, valves, valve-seats, transmissions and gears. Heat-treating is then considered in some detail, three specific reasons for annealing before machining being given and five which are governing factors in regard to heat-treatment in general.

Stating that it is conceded by engineers that weight reduction is desirable economically but that it is not unusual to find that weight reduction is looked upon as incompatible with reliability and road-holding properties, the author outlines briefly the normal weight-distribution in an automotive vehicle and gives a short analysis of the power required to drive it having in mind the necessity of reducing the absolute friction-loss. The use of aluminum for various parts is debated, especially those in which reliability is distinctly a function of lightness and not of weight such as engine pistons, and the application is made general to cover all parts of an automobile in which the stresses are determined by road shocks and speed. The trend of design in general and recent research in particular are stated to be along the lines of weight reduction without any sacrifice of essentials.

The author describes the type, size and general characteristics of the engines with which the German submarines were equipped at the time of the surrender, after having personally inspected 183 of them at that time, and then presents the general details of construction of these engines, inclusive of comments thereon. The maneuvering gear for such engines receives lengthy consideration and the reliability of engines of this type is commented upon in some detail, the author having confirmed his opinion that the German submarine engine is extremely reliable. One of the controlling factors in the design is that the Germans had investigated steel casting to the point where the successful production of steel castings was an ordinary process, and the author believes this to have been largely responsible for the success of the German submarine engine.

The paper is devoted more especially to enclosed body construction, with the object of creating a closer relation between the chassis and the body designer, from the viewpoint of an automotive body constructor. After enumerating what are probably the most important materials that enter into enclosed-body construction, inclusive of glue, the author outlines what constitutes the proper seasoning of wood, this being very important because very little all-metal or steel construction has been developed as yet for enclosed bodies, owing to the fact that many parts are required that necessitate using wood. Chassis deflection is discussed in its relation to enclosed-body construction and an outline is presented of body-construction development in general. The author believes that body construction will not be changed radically until either the basic type of design or shape is transformed or there is a firmer foundation to build upon.